Some of the "magic pills" for fat loss sold today aren't capsules at all. They are schedules. Eat only between noon and eight. Fast one day, feast the next. The pitch is the same as any fat-burner bottle: change one thing, and the weight comes off without much effort. Two clinical trials put meal timing to that test, and their results are worth knowing before you set an alarm for your first meal.
The eight-hour window, tested on 116 people
Lowe and colleagues at the University of California, San Francisco ran a 12-week randomised trial of 16:8 eating (PubMed 32986097). One group ate whatever they liked from 12:00 pm to 8:00 pm and took no calories from 8:00 pm until noon the next day. The other group ate three structured meals a day. Participants were adults aged 18 to 64, they lived anywhere in the United States, and each got a Bluetooth scale. 116 people were included.
The time-window group lost 0.94 kg. The three-meals group lost 0.68 kg. The difference between them, 0.26 kg, was not statistically significant. The authors' conclusion is blunt: eating within a time window, with nothing else changed, "is not more effective in weight loss than eating throughout the day." Among the people tested in person, estimated energy intake did not differ between the groups. The clock did not quietly cut anyone's calories.
Fasting every other day, tested for a year
Trepanowski and colleagues in Chicago followed 100 adults (86 women, 14 men) for a full year (PubMed 28459931). One group fasted on alternate days, eating 25% of their energy needs on fast days and 125% on "feast days". A second group ate 75% of their needs every day. A third group changed nothing. Six months of weight loss were followed by six months of trying to hold it.
At month 6, both diet groups had lost 6.8% of body weight compared with the control group. At month 12 the figures were 6.0% for alternate-day fasting and 5.3% for daily restriction. The fasting group was the most likely to quit: 13 of 34 dropped out, against 10 of 35 on daily restriction. They also ate more than prescribed on fast days and less than prescribed on feast days. The authors concluded that alternate-day fasting "did not produce superior adherence, weight loss, weight maintenance" compared with daily calorie restriction.
What the two trials share
Neither trial says meal timing is useless. The time-window group and both Chicago diet groups lost weight. But in San Francisco, three ordinary meals did about as well as the window. In Chicago, people who simply ate 75% of their needs every day did about as well as the fasters. If a window or a fasting day helps you stick to eating less, fine. These two trials give no sign that the timetable works on its own.
The NHS weight-loss tips point the same way, without any special schedule. They suggest aiming to lose 0.5 to 1kg a week, reading food labels, and swapping sugary drinks for water. One item cuts against the skip-breakfast fashion: "do not skip meals – you might end up snacking more because you feel hungry."
Where dates fit in a plain eating day
Dates are a dried fruit, and the NHS counts "a 30g portion of dried fruit, such as currants, dates, sultanas and figs" as one of your 5 A Day. The same line adds that dried fruit "should be eaten at mealtimes, not as a snack between meals, to reduce the impact on teeth." Whatever eating hours you keep, the advice is to put dates inside a meal.
They are not low in energy. USDA FoodData Central lists Deglet Noor dates at 282 kcal per 100g and Medjool at 277 kcal per 100g, so a 30g portion comes to roughly 83 to 85 kcal. One pitted Medjool date weighs about 24g. That is useful to know if you are counting, and it is the kind of number a timing plan can't change. Piarom, the dark, semi-dry Iranian date this site is named after, has no entry in FoodData Central, so we don't quote figures for it.
For more plain reading on dates and food, see the blog. More about this site is on the About Us page and the contact page.
This article is general information, not personal advice. Speak to a GP or dietitian before starting a fasting plan.